The fibers used to compose heat-proof protective wear worn by firemen during extinguishing operations have conventionally been noncombustible asbestos fiber, glass fiber and the like, but heat-proof flame retardant organic fibers such as aramid fibers, polyphenylene sulfide fibers, polyimide fibers, polybenzimidazole fibers and polybenzoxazole fibers have come to be most commonly used in recent years because of environmental problems, and for greater mobility.
In order to prevent radiant heat into fabrics as well, many products are surface-treated by coating, vapor deposition, sputtering or plating of metallic aluminum or the like, and these are used as front fabric layers. Heat-insulating properties against radiant heat have been improved considerably by such methods.
In recent years, especially, as preventing radiant heat has become an extremely important specification, Approach A of ISO 11613 assigns specifications of at least 13 seconds and at least 18 seconds for a flame exposure test (ISO 9151) and a radiant heat exposure test (ISO 6942-2002), respectively.
Furthermore, in order not only to provide heat resistance but also to prevent heat stroke by heat stress during work activities in the summer season, methods used in recent years have included those that employ ice packs in inner layers, and ensuring air permeability by sewing. Lightweightness is another means of reducing heat stress that has become an issue of interest in recent years.
Such heat-proof protective wear includes protective wear with a two-layer structure as disclosed in Japanese Unexamined Patent Publication No. 2006-16709, and front fabric layers composed of differential-shrinkage spun yarn, as disclosed in Japanese Unexamined Patent Publication No. 2009-280942, but the necessary performance has often been inadequate, or sufficient lightweightness has not been achieved, and as a result the heat-proof protective clothing has not been fully satisfactory.